Fluorescence Array-Based Sensing Of Metal Ions Using Conjugated Polyelectrolytes

Since the beginning of industrialization, heavy metal pollution in water and soil sources has remained a serious problem that impacts human health and sustainable development.Although commonly-used methods such as atomic absorption spectrometryand inductively-coupled plasma mass spectrometry(ICP-MS) have provided accurate measurements of metal ions, the inconvenience, high cost, and inflexibility foruse in on-site analysis of these methods impede their use. Therefore, developing new sensing materials and methods for metal ions has always been of great interest to researchers.Conjugated polyelectrolytes(CPEs) have been widely used as sensing materials due to their advantages, such as fluorescent signal amplification and feasible structural modification. Array-based method describes that a series of sensors are combined into an array, in which each individual sensor responds differently to many analytes, and a requirement for selective affinity is unnecessary, greatly reduces the design effort. This thesis combines the advantages of conjugated polyelectrolytes and array-based method, providing a simple, fast method for metal ion detection.The main contents include:1. As conjugated polyelectrolytes with different side chains interact with metal ions differently, we designed and synthesized four anionic CPEs(PPE1, PPE2, PPE-IDA and PPE-HPA) which share a poly-paraphenylene ethynylene(PPE) backbone but were modified with different pendant ionic side chains. And their synthetic routes and methods are described. Bseides, we conducted a UV-visible absorption and fluorescence emission spectra characterization and researched in the photophysical properties of these four conjugated polyelectrolytes.2.Through performing research on the quenching properties by metal ions of four negatively charged and a positively charged conjugated polyelectrolytes, positively charged PPE-N+ was precluded in order to improve the detection efficiency in constituting the sensor array. By construction of fluorescence signal response pattern of the sensor array to metal ions, the results show that the response pattern features of eight metal ions are obvious and can be distinguished by the naked eye.3. LDA(Linear Discrimination Analysis) is a statistical analysis method that can visually differentiate between two or more kinds of objects or events based on their linear combination of features. We performed dimensionality reduction to multidimensional fluorescence signal response pattern data through LDA, constructing 2-D and 3-D analysis diagram to identify and study the relationship between sensing efficiency of the sensor array and the number of constituent units. Results show that the sensor array based on four PPEs can be most effective, fast and easy to detect 8 kinds of toxic metal ions, the detection limit of less than 100 nM. Moreover, the sensor array capable of Pb2+ and Hg2+ concentrations were estimated at 100 n M-20 μM concentration range, with good accuracy.